Metachrome dyeing procedure and products dyed therewith



Patented Aug. 22, 1950 METACHROME DYEING PROCEDURE AND PRODUCTS 'DYED THEREWITH Chester A. Amick, Bound Brook, and George L. Royer, North Plainfield, N. J.,. assignors .to

American Cyanamid Company,

New York,

N. Y., a corporation of Maine No Drawing. Application December '7, 1948, Serial No. 64,037-

6 Claims.

This invention relates to an improved metachrome process in which basic nitrogenous fibres such as wool are dyed in a metachrome bath containing a suitable salt or compound of chromiumfor-metallizing purposes and a soluble salt of a metal of the B family ofthe second group of the periodic system.

The ordinary metachrome process is used to dye wool and similarfibres'by means of a dye bath which contains a. soluble chromium compound; the dyeing usually proceeding on the acid side. The metachrome process has been used practically only with a few-colors because with'many. colors it has been difficult to obtain adyeing of suitable strength and levelness. It has-been proposed in the past toincrease the. penetration by the presence of a cationic surface active agent but this. has not woven-satisfactory inpractical operation because the cationic surface active agent reacts withthe constituents of thedye bath to produce insoluble colored material whichtends to form-a colored scumresulting inspotty or uneven dyeing.

In the prior patent of which we are inventors No.. 2,434,178 there isdescribed a metachrome process in which the difiiculties of scum formation have been avoided by using a colloidized cationic surface active agent. This resulted in a great advance and made the metachrome process practical in many instances where it was formerly not consideredsuitable. However, the maximum strength obtainable was not greatly increased over that which was known before and this still left room for an improved process which could retain the level dyeing but produce a still stronger shade.

The present invention achieved such a result by the addition of two features to the dyeing process claimed in the earlier patent. The first and most important feature is the presence of a soluble compound of a metal of the B family of the second group of the periodic system. This family includes the well known metals zinc and cadmium. The second feature is that the pH of a dye bath to start is alkaline but not greater than 9.5 and is gradually rendered more acid until finally the acidity reaches a point not lower than the isoelectric point of wool, about pH 4.0 at the end of the dyeing procedure.

The mechanism by which the salts of the metals of the B family of the second group of the periodic system act to produce increased strength of shade is not known. It does not appear to be a question of the metals actuall adding on to the complex because there are sufiicient chrom ium compounds present. to completely metallize the dye-before the..dyeingiscompleted. It is. therefore notdesired to limit the present inven.-- tion to any particular theory of why the increased'strength of shade is obtained.

Except for the change in pHduring the dyeing procedure no new'techniques need-to be learned by the dyer asthe process proceeds in am nner which is conventional in the dyeingofqwool by the metachrome process. advantage. The addition of acid is not a critical matter, any suitable acid which does not react with the dyestufi's may .:be employed. 'F'orthis purpose acetic acid presents many practicaliad vantages and is the preferred-acid althoughthe ordinary mineral acids :such as hydrochloric and suli uric acids may also be used.

It is an advantage. of the present invention that strong dyeings are obtainable with all of the ordinary chrome dyes which are susceptible to the metachrome process and even some-which were not considered suitable in the past. In fact the general applicability of the process to chrome colors is one of; its most important practical advantages. While the process may be used with a wide'number of dyestuffs nevertheless it should be realized that there is some'variation in behavior from dyestufiwto dyestuffand therefore the invention is of particular importance in connection with thosedyes which are readily yed by he metachrom process whereshades and maximum Strength are desired. On the. other hand when such great strength is not required.

the present invention opens up the field of. meta-. chrome dyeing to a number of dyes which were not of practical importance hitherto.

Although the improved strength of shade, levelness of dyeing andgood penetrationisperhaps the most important single result of the present invention it is afurther advantage that exhaustion is. more complete which results me Where the in boiling water, 10 parts of 28% aqueous ammonium hydroxide, 5 parts oi a nonionic stir This is a practical face active agent prepared by reacting 2 111615 of polyethylene oxide (molecular weight 4,000) and 1 mol of the dimerized acid obtained by heat treating soya bean acid and distilling oil the monomeric acid, 2 /2 parts of the condensation product of octadecylguanidine bicarbonate and 6 parts of ethylene oxide, parts of cadmium chloride, 3 parts of potassium bichromate, and water to bring the volume of the bath up to 40,000 parts.

500 parts of woolen yarn or goods are prewet with water and entered into the dye bath at 110 F. The dye liquor is brought to the boil in half an hour with frequent turning of the wool to insure uniform dyeing. Boiling and turning are continued for another half hour after which 10 parts of 28% acetic acid are added and boiling and turning continued for a further half hour. Then parts of 28% acetic acid is added and boiling and turning continued for a third half hour.

1 A control dyeing is made by the usual metachrome process, the bath consisting of 10 parts of dyestuff previously dissolved in boiling water,

50 parts of ammonium sulfate, 5 parts of potassium bichromate and sufficient water to bring up the dye bath to 40,000 parts.

The wool dyed by the first bath when examined by a recording spectrophotometer shows an increase in strength over the control dyeing of about 232%.

Example 2 The procedure of Example 1 is repeated but 10 parts of zinc chloride are used in place of the cadmium chloride. A skein dyed in the presence of the zinc chloride is about 265% stronger than the control dyeing.

Example 3 The procedure of Example 2 is repeated but using a different dyestuff having Color Index 652. The strength of the dyed wool is 95% greater than the control dyeing.

Example 4 The procedure of Example 1 is followed using the dyestuif of Example 3. The wool dyed in the bath containing the cadmium salt has a strength 75% greater than that of the control dyeing.

Example 5 The procedure of Example 1 is followed but a different dyestuff is used having Color Index No. 1034. The wool dyed in the bath containing cadmium chloride is 28% greater in strength than the control value.

Example 6 The procedure of Example 1 is followed using, however, a dyestuff having a Color Index No. 299. The color value of the dyed goods from the bath containing the cadmium chloride is greater than that of the control dyeing.

Example 7 The procedure of Example 1 is repeated except the dyeing is made on nylon. The dyeing made in the bath containing the preferred features is very much stronger than that made in the control bath.

Example 8 Procedure of the preceding example is repeated exactly except the dyeing is made on real silk. Again the color value of the dyeing and the penetration of the fibers is excellent.

We claim:

1. A method of dyeing which comprises subjecting a substantially unmetallized basic nitrogenous fiber to the action of a dye bath formed by mixing a chromable dye, a soluble chromium compound, a cationic surface active agent, a soluble salt of a metal of group IIb of the periodic system, water, and sumcient alkali to make the pH of the bath alkaline but not greater than 9.5 and to cause said dye to react with said group II--b metal salt to form a group II-b metal complex of said dye, partially dyeing said fiber from said complex, gradually lowering the pH of said bath to a point where decomposition of said compl x and chromation of the dye take place, and completing the dyeing at a pH of not less than about 4.0.

2. A method according to claim'l in which the basic nitrogenous fibre is wool.

3. The method according to claim 2 in which the soluble compound of the metal of the B fam-' REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 661,985 Haussmann Nov. 20, 1900 941,399 Winslow Nov. 30, 1909 2,434,178 Royer 'Jan. 6, 1948 FOREIGN PATENTS Number Country Date 821,992 France Sept. 6, 1937 OTHER REFERENCES Amer. Dyes. Rep. for Sept. 8, 1947, page P495.

Smiths Inorganic Chemistry, revised by Kendall, published in N. Y. C. by Century 00., 1926, page 794. 

1. A METHOD OF DYEING WHICH COMPRISES SUBJECTING A SUBSTANTIALLY UNMETALLIZED BASIC NITROGENOUS FIBER TO THE ACTION OF A DYE BATH FORMED BY MIXING A CHROMABLE DYE, A SOLUBLE CHROMIUM COMPOUND, A CATIONIC SURFACE ACTIVE AGENT, A SOLUBLE SALT OF A METAL OF GROUP II-B OF THE PERIODIC SYSTEM, WATER, AND SUFFICIENT ALKALI TO MAKE THE PH OF THE BATH ALKALINE BUT NOT GREATER THAN 9.5 AND TO CAUSE SAID DYE TO REACT WITH SAID GROUP II-B METAL SALT TO FORM A GROUP II-B METAL COMPLEX OF SAID DYE, PARTIALLY DYEING SAID FIBER FROM SAID COMPLEX, GRADUALLY LOWERING THE PH OF SAID BATH TO A POINT WHERE DECOMPOSITION OF SAID COMPLEX AND CHROMATION OF THE DYE TAKE PLACE, AND COMPLETING THE DYEING AT A PH OF NOT LESS THAN ABOUT 4.0. 